Table 3 Univariate and multivariate model of local progression-free survival after 18 Gy stereotactic radiosurgery

Gross tumor volume

≤ 0.3 cm³ (reference)

0.430

0.015

> 0.3 cm³

1.249

0.720, 2.166

2.229

1.172, 4.239

Extracranial metastases

No (reference)

0.360

0.828

Yes

1.318

0.730, 2.379

1.107

0.442, 2.771

Control of primary cancer

No control (reference)

0.784

0.105

Control

0.924

0.524, 1.628

0.581

0.301, 1.119

Karnofsky performance score

0.972

0.940, 1.004

0.089

0.976

0.927, 1.028

0.359

Systemic treatment * 3 months before/after SRS

No (reference)

0.101

0.073

Yes

0.481

0.201, 1.154

0.385

0.136, 1.094

Number of brain metastases

1.035

0.839, 1.276

0.750

0.926

0.719, 1.192

0.550

Patient age

0.992

0.973, 1.011

0.414

0.987

0.963, 1.011

0.295

Recursive partitioning analysis (RPA)

0.926

0.559, 1.534

0.764

0.701

0.359, 1.366

0.297

Diagnosis-specific graded prognostic assessment (ds-GPA)

0.800

0.583, 1.098

0.166

0.678

0.365, 1.258

0.218

Histology

Other (reference)

0.084

0.018

Malignant melanoma/renal cell cancer/sarcoma

1.648

0.935, 2.905

2.330

1.155, 4.699

Cerebral progression outside the planning target volume

No (reference)

0.699

0.397, 1.910

0.729

Yes

1.132

0.603, 2.127

0.870